Poutine originated in the 1950's, but the details are cloudy. It seems to have first turned up in Quebec; the most common story of its origin references Warwick, near Montreal.
Classic Montreal poutine uses a special pepper sauce. There are many modern variations, with meat or other items added. Sometimes the sauce is replaced with something else (such as spaghetti sauce).
Etymology: the origin of the name itself is similarly cloudy. The most likely source seems to be a French-derived slang term for "mess" or "unappetizing mixture of leftovers". It's also suggested that the word might be related to 'pudding'. The word 'poutine' itself has many definitions that pre-date the birth of the dish.
In Canada, poutine is often served at fast food restaurants, as an alternative to plain fries. In the U.S., it can be found in some restaurants in border states; I first encountered non-Canadian poutine at a Milwaukee, WI, bar.